Flow distributor for fiber material for use in connection with paper making machines



Oct. 3, 1961 H. MEYER 3,002,558

FLOW DISTRIBUTOR FOR FIBER MATERIAL FoR USE IN CONNECTION WITH PAPER MAKING MACHINES 2 Sheets-Sheet 1 Filed Dec. 18, 1958 Fig. 2

Oct. 3, 1961 H. MEYER 3,002,558

FLOW DISTRIBUTOR FOR FIBER MATERIAL FOR USE IN CONNECTION WITH PAPER MAKING MACHINES 2 Sheets-Sheet 2 Filed Dec. 18, 1958 3,002,558 FLOW DISTRIBUTOR FOR FIBER MATERIAL FOR USE IN CONNECTION WITH PAPER MAKING MACHINES Heribert Meyer, Chillicothe, Ohio, assignor to J. M. Voith G.m.b.H., Heidenheim (Brenz), Germany Filed Dec. 18, 1958, Ser. No. 781,296 Claims priority, application Germany Dec. 21, 1957 14 Claims. (Cl. 162-338) The uniform distribution of the stock suspension over the entire width of the machine wire is an important requirement for the manufacture of a satisfactory paper, carton or the like. By uniform distribution, the paper maker understands uniform flow velocity, uniform concentration as Well as constant height of the suspension at the exit from the slice of the headbox over the entire width of the wire. Moreover, for purposes of obtaining a uniform transparency or clearness of the paper it is required that the suspension when leaving the headbox will for purposes of maintaining the fiber mixture, be in a constant turbulent condition extending over the width of the slice of the headbox.

The difliculty of meeting these requirements consists primarily in that the suspension is fed to the paper machine through feeding conduits of relatively small cross sections, and that uniform distribution over the width of the sheet to be made, which width may be up to 8.75 yards, is to be effected in a minimum of space.

For transforming the mostly circular flow cross section of the feeding line into the required rectangular flow cross section ahead of the slice, various embodiments of so-called transverse flow distributors have been suggested. With all transverse flow distributors, the suspension enters laterally, i.e. transverse to the direction of movement of the paper sheet and is deviated once or a plurality of times while in most instances it is additionally subjected to "a throttling by slots, perforated plates, perforated drums or the like which have approximately the same width as the slice or the papersheet. For purposes of avoiding a non-uniform velocity distribution over the Width of the slice as obtained when dealing with a unilateral inflow of the suspension, it is known to provide both sides of the transverse flow distributors with feeding conduits, and to sub-divide the transverse flow distributors int-o two deviating chambers by means of partitions extending in diagonal direction. The said chambers will thus be provided with tapers extending in opposite direction with regard to each other. The inlet into the deviating chambers is respectively arranged on the larger end side so that two currents with oppositely arranged directions of flow will flow into the transverse distributor. Both flows are respectively deviated in the chambers and combine with each other in a mixture chamber or mixing path mostly after having passed through one or more throttling points.

In spite of the tapering of the deviating chamber and in spite of the arrangement of throttling points, with the heretofore known transverse flow distributors, it cannot be avoided that a dis-uniform velocity adjustment over the width of the deviating chamber outlet will be obtained, in other words, the velocity distribution will increase over the width. For this reason, when looking in the direction of flow, behind the deviating chambers there is arranged a mixing chamber or mixing path in which the flows from the two deviating chambers are mixed over the width of the mixing chamber in order to obtain a uniform velocity. In said mixing chamber, especially in the outer marginal zones thereof, a flow of higher velocity from one chamber hits upon a flow of lower velocity from the other chamber. This encounter atent 'ice of the flows has the great disadvantage that individual turbulences, so-called erratic whirls, will form. These turbulences may remain in the suspension up to the machine wire by remaining superimposed upon the turbulence suspension flow and may harmfully afiect the formation of a paper with uniform transparency. Such individual turbulences may also form when deviating the suspension a plurality of times. Furthermore, the individual turbulences impede the uniform distribution of the concentration of the suspension inasmuch as they favor local de-rnixing of the suspension. This situation is brought about by the fact that fiber suspensions are thixotropic with regard to their flow properties, i.e. have the tendency of de-mlxing in View of larger local shearing stresses. Such shearing stresses will occur in particular at points where the velocity drops, which means also within the surrounding of the individual turbulences.

It is, therefore, an object of the present invention to provide an arrangement which will overcome the above mentioned drawbacks.

It is another object of this invention to provide a flow distributor for use in connection with paper making machines which will avoid the formation of individual turbulences.

It is also an object of this invention to provide a flow distributor of the type set forth in the preceding paragraph, which will also avoid deviating losses and the formation of dead Water zones behind the distributing screen which favor the formation of individual turbulences and the settling of fibers.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIGS. 1 and 2 respectively show a vertical and horizontal longitudinal section of a transverse flow distributor with distributing screen. FIG. 2 is a sectional fragmentary view taken along the line 11-11 of FIG. 1.

FIGS. 3 and 4 respectively illustrate in vertical and horizontal longitudinal section a transverse flow distributor with disc straightener.

General arrangement In order to overcome the drawbacks of the heretofore known transverse flow distributors, particularly in order to avoid individual turbulences, with flow distributors with one deviation only of the suspension there is suggested in conformity with the present invention to provide the flow distributor with a single deviating chamber extending over the entire width of the headbox and having a constant cross section while the feed is arranged unilaterally in a manner known per se. Furthermore, in the outlet of the deviating chamber there is arranged a device for steadying the flow of the paper stock and obtaining uniform velocity distribution, said device being designed as a flow evener provided with guiding vanes approximately perpendicular to said plane and to the dimotion of feed. The longitudinal extension of said guiding vanes is a multiple of the thickness thereof, whilethe remaining free cross section of the passage is substantially less than the cross section of the deviating chamber at the inlet.

Such a design of the flow distributor which will henceforth be called one-flow distributor, prevents the formation of individual turbulences because the flow is deviated only once and in the same plane, and the mixture of two flows is avoided. Furthermore, a constant speed distribution with the exception of minor marginal zones is obtained over the entire width of the one-flow distributor. This effect is surprising inasmuch as with the heretofore known flow distributors with one deviation only of the suspension, in spite of the installation of culty consists in the lack of a rectifier of the flow at the exit from the deviating chamber.

Structural arrangement With the embodiment shown in FIGS. 1 and 2, the suspension passes to the one-flow distributor through a pipe 4 and is distributed in the deviating chamber 6 over the width thereof. The suspension then passes through a flow evener -8 into the headbox 1 from where the suspension passes through the slice 3 onto the machine wire 2.

The one-flow distributor is formed substantially by the deviating chamber 6 which has a cross section that is substantially constant seen in direction of said chamber entrance. One lateral side is designed as inlet 5 having connected thereto a feeding conduit 4. A longitudinal side of the deviating chamber 6 is provided with an outlet 7. Arranged in said outlet 7 is the flow evener 8 designed as straightener, said flow evener consisting of a great number of guiding vanes 9 vertically arranged alongside each other and slightly spaced from each other. According to this embodiment, the guiding vanes have advantageously a length which is about eight times the thickness thereof. The total cross section of the space between the individual guiding vanes 9 is so selected as to correspond approximately 0.4 times to the inlet cross section at 5 into the deviating chamber.

In order to prevent deviating losses at the entrance side, according to a further embodiment of the present invention, the guiding vanes of the flow-evener are rounded. According to a further modification, instead of rounding the guiding vanes at the entrance thereof, it is also possible to design the entrance edges as round bars which are rotatably inserted into the top and bottom Walls and provided with a drive common thereto. More specifically, the inlet edges of the guiding vanes 9 are designed as round bars 10 arranged close to the guiding vanes 9 and pertaining thereto but rotatable about their own axes. The round bars 10 are connected by means of levers 11 to a control rod 12 common thereto. Control rod 12 is by means of a drive (not shown in the drawings) so actuated that an oscillating movement will be imposed upon said bars 10.

In order to prevent the formation of dead water zones behind the flow evener, which dead water zones favor the formation of individual turbulences and the settling of fibers, the guiding vanes are sharp edged at the exit side, i.e. the guiding vanes taper in the direction of flow and merge at the exit side of flow evener 8 into sharp edges. The velocity of the suspension will at constant height of the passage decrease in conformity with said taper. Therefore, advantageously, the cross section of the passage is decreased in conformity with the taper of the guiding vanes. More specifically, in order to compensate for the increase in the cross section of the passage of the flow evener, said increase, as stated above being caused by the taper, and in order to prevent a drop in the velocity of the suspension flow, said drop being inherent to the increase in said cross section, the bottom side of the passage in which the guiding vanes 9 is arranged are provided with an inclined wall 13 converging in the direction of the flow.

After the suspension has passed through the flow evener, it enters a chamber 14 in which minor irregularities of the flow as caused by the guiding vanes will be equalized.

It may be added that in the deviating chamber 6 the 4 static pressure increases in the direction toward that side which is opposite to the inlet. As a result thereof, the marginal layers of the flow in that portion of the deviating chamber which is remotest from the inlet, namely at the wall opposite to the flow evener or disc straightener, maydetach themselves from the adjacent wall and form dead Water zones with a flow of its own movement. Such dead water zones favor the undesired settling of stuff particles, especially heavy stuff particles. Therefore, in order to avoid such dead zones, the deviating chamber is advantageously rounded at the respective corners. A further possibility of avoiding dead water zones consists in that in the said corners at the bottom of the deviating chamber 6, or at the top wall or on one side wall of the deviating chamber 6 small discharge openings are provided. By means of a pump certain quantities of suspension are continuously withdrawn through said openings so that at said corners a continuous flow will prevail which will prevent the formation of dead water zones.

As already mentioned, in the lateral marginal zones of the flow behind the flow evener 8 or disc straightener 20, a small drop in the velocity may occur in view of the friction on the side walls of the deviating chamber outlet '7. In order to avoid that this drop in velocity will have an unfavorable effect in the slice 3, the marginal zones on one or both sides of the flow, while flowing in the direction toward said slice, will be withdrawn through discharge conduits 17. To this end, the deviating chamber 6 is expediently wider than the slice 3 in conformity with the cross section of said withdrawing conduits.

More specifically, with regard to FIGS. 1 and 2, for purposes of avoiding the formation of dead water zones, portion 15 of the deviating chamber 6 is provided with discharge openings 16 through which a portion of the suspension is continuously withdrawn. The discharge openings 16 are arranged in the bottom. However, they may also be arranged in the top wall and/ or in one side Wall of the deviating chamber 6.

For discharging the lateral marginal zones at a lower velocity, one side of the said chamber =14 has toward the collecting chamber arranged a discharge conduit 17 through which said marginal zones are Withdrawn in a continuous manner.

In conformity with a further development of the invention, it is possible to replace the flow evener consisting of individual vanes by a set of round discs on a shaft common thereto While arranging said discs alongside each other at a slight distance from each other. The shaft of the device henceforth designated as disc straightener may be driven through a transmission by a motor so that the discs will rotate at a slower rate. The disc straightener Will also assure a proper straightening of the flow. More specifically, with regard to FIGS. 3 and 4 of the drawings, the transverse flow distributor shown therein differs from the above mentioned flow distributor of FIGS. 1 and 2 primarily in the arrangement of the disc straightener 18 instead of the flow evener 8. The disc straightener is formed of a great number of round discs 20 which are arranged alongside each other ona shaft 19 and are slightly spaced from each other. Shaft 19 is driven by a motor 21 through the intervention of a transmission 22 so that the discs are rotated at low speed.

For the purpose of designing the inlet into the disc straightener for most favorable flow conditions, the diameter of the discs is greater than the height of the inlet and/ or outlet of the deviating chamber. The height of the cross section of the passage of the disc straightener is advantageously limited by intermediate walls provided between the discs to limit the height of the inlet and outlet openings. Furthermore, during rotation of the discs said walls continuously clean the discs from adhering fibers.

More specifically, with regard to FIGS. 3 and 4, the diameter of disc 20 is greater than the height of the inlet and outlet 7 of the deviating chamber 6. The height of the flow cross section of the disc straightener 18 is limited to the height of outlet 7 by means of intermediate walls 23 and 24 respectively between the discs 20. The smallest clear cross section of the disc straightener is determined by the diameter of the shaft 19 which has to be designed so as to absorb the forces acting upon said shaft. In order to be able to design the shaft diameter independent of said forces, the discs are journalled on rollers outside of said intermediate walls so that the load on the shaft will be greatly reduced. More specifically, in order to be able to absorb a considerable portion of the forces acting upon the shaft 19, the discs 20 are journalled on rollers 25.

It is, of course, to be understood that the present invent-ion is, by no means, limited to the particular constructions shown in the drawings but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. In a transverse flow distributor having only one deviation of the flow, especially for connection with a headbox of a paper machine: a deviating chamber provided with only one paper stock inlet and with only one paper stock outlet, said paper stock inlet being arranged unilaterally of said deviating chamber, said deviating chamber having a substantially constant cross section seen in the direction of said paper stock inlet, a device for steadying the flow of the paper stock and obtaining uniform velocity distribution, said device being designed as distributing screen means arranged in said stock outlet and including guiding vanes each having a length equalling at least a multiple of the thickness thereof and said vanes extending substantially perpendicular to the direction of the inflow of the stock and being slightly spaced from each other, the remaining free passage cross section between said spaced guiding vanes being considerably less than the cross section of said stock inlet of the deviating chamber. i

2. A transverse flow distributor according to claim 1, in which the ratiov of said free passage cross section between said spaced guiding vanes to the cross section of said stock inlet into the derivating chamber amounts to about 0.4.

3. In a transverse flow distributor having only one deviation of the flow, especially. for connection with a head-box of a paper machine: a deviating chamber provided with only one paper stock inlet and with only one paper stock outlet, said paper stock inlet being arranged unilaterally of said devicating chamber, said deviating chamber having a substantially constant cross section seen in the direction of said paper stock inlet, a device for steadying the flow of the paper stock and obtaining uniform velocity distribution, said device being designed as distributing screen means arranged in said stock outlet and including guiding vanes each having a length equalling at least a multiple of the thickness thereof while the entrance side of said guiding vanes is well rounded and the exit side of said guiding vanes is sharp-edged, said guiding vanes extending substantially perpendicular to the direction of the infiow of the stock and being slightly spaced from each other, the remaining free passage cross section between said spaced guiding vanes being considerably less than the cross section of said stock inlet of the deviating chamber.

4. In a transverse flow distributor having only one deviation of the flow, especially for connection with a headbox of a paper machine: a deviating chamber provided with only one paper stock inlet and with only one paper stock outlet, said paper stock inlet being arranged unilaterally of said deviating chamber, said deviating chamber having a substantially constant cross section seen in the direction of said paper stock inlet, said paper stock outlet forming a passage including top and bottom sides and having one of said last mentioned sides inclined in the direction of the flow of the stock, a device for steadying the flow of the paper stock and obtaining uniform velocity distribution, said device being designed as distributing screen means arranged in said stock outlet and including guiding vanes each having a length equalling at least a multiple of the thickness thereof and said vanes extending substantially perpendicular to the direction of the inflow of the stock and being slightly spaced from each other, the remaining free passage cross section of said spaced guiding vanes being considerably less than the cross section of said stock inlet of the deviating chamber.

5. In a transverse flow distributor having only one deviation of the flow, especially for connection with a headbox of a paper machine: a deviating chamber provided with only one paper stock inlet and with only one paper stock outlet, said paper stock inlet being arranged unilaterally of said deviating chamber, said deviating chamber having a substantially constant cross section seen in the direction of said paper stock inlet, a device for steadying the flow of the paper stock and obtaining uniform velocity distribution, said device being designed as distributing screen means arranged in said stock outlet and including guidingvanes each having a length equalling at least a multiple of the thickness thereof, the ends of said guiding vanes at the entrance of the stock into said distributing screen means respectively being designed as rotatable bars, said guiding vanes extending substantially perpendicular to the direction of the inflow of the stock and being slightly spaced from each other, the remaining free passage cross section between said spaced guiding vanes being considerably less than the cross section of said stock inlet of the deviating chamber.

6. In a transverse flow distributor having only one deviation of the flow, especially for connection with a headbox of a paper machine: a deviating chamber provided with only one paper stock inlet and with only one paper stock outlet, said paper stock inlet being arranged unilaterally of said deviating chamber, said deviating chamber having a substantially constant cross section seen in the direction of said paper stock inlet, a plurality of round discs slightly spaced from each other and axially arranged alongside each other in said stock outlet, a shaft common to all of said discs and supporting the same while being rotatably connected thereto, said discs forming circular guiding vanes, each having a diameter equalling at least a multiple of the thickness thereof, and the remaining free passage cross section between said guiding vanes being considerably less than the cross section of said stock inlet of the deviating chamber.

7. A transverse flow distributor according to claim 6, which includes motor means and also transmission means drivingly connecting said motor means with said shafts for rotating the same.

8. In a transverse flow distributor having only one deviation of the flow, especially for connection with a headbox of a paper machine: a deviating chamber provided with only one paper stock inlet and with only one paper stock outlet, said paper stock inlet being arranged unilaterally of said deviating chamber, said deviating chamber having a substantially constant cross section seen in the direction of said paper stock inlet, a plurality of round discs slightly spaced from each other and axially arranged alongside each other in said stock outlet, a shaft common to all of said discs and supporting the same while being rotatably connected thereto, each said disc having a diameter in excess of the height of the stock inlet of said deviating chamber, and intermediate walls interposed between said discs for limiting the height of the free passage cross section between said discs to the height of said stock inlet.

9. A transverse flow distributor according to claim 8, which includes roller bearing means supporting said discs.

10. In a transverse flow distributor having only one deviation of the flow, especially for connection with a headbox of a paper machine: a deviating chamber provided with only one paper stock inlet and with only one,

paper stock outlet, said paper stock inlet being arranged unilaterally of said deviating chamber, said deviating chamber having a substantially constant crosssection seen in the direction of said paper stock inlet, a plurality of round discs slightly spaced from each other and axially arranged alongside each other in said stock inlet, a shaft common to all of said discs and supporting the same while being rotatably connected thereto, each said disc having a diameter in excess of the height of the stock Outlet of said deviating chamber, and intermediate walls interposed between said discs for limiting the height of the free passage cross section between said discs to the height of said stock outlet.

11. A transverse flow distributor according to claim 10, which includes roller bearing means supporting said discs.

12. In a transverse flow distributor having only one deviation of the flow, especially for connection with a headbox of a paper machine: a deviating chamber provided with only one paper stock inlet and with only one paper stock outlet, said paper stock inlet being arranged uni-laterally of said deviating chamber, said deviating chamber having a substantially constant cross section seen in the direction of said paper stock inlet, and having a well rounded rear wall which is located opposite said stock inlet, a device for steadying the flow of the paper stock and obtaining uniform velocity distribution, said device being designed as distributing screen means arranged in said stock outlet and the including guiding vanes each having a length equalling at least a multiple of the thickness thereof and said vanes extending substantially perpendicular to the direction of the inflow of the stock and being slightly spaced from each other, the remaining free passage cross section between saidspaced guiding vanes being considerably less than the cross section of said stock inlet of the deviating chamber.

13. In a transverse flow distributor having only one deviation of the flow, especially for connection with a headbox of a paper machine: a deviating chamber provided with only one paper stock inlet and with only one paper stock outlet, said paper stock inlet being arranged unilaterally of said deviating chamber, said deviating chamber having a substantially constant cross section seen in the direction of said paper stock inlet, a device for steadying the flow of the paper stock and obtaining uniform velocity distribution, said device being designed as distributing screen means arranged in said stock outlet and including guiding vanes each having a length equalling at least a multiple of the thickness thereof and said vanes extending substantially perpendicular to the direction of the inflow. of the stock and being slightly spaced from each other, the remaining free passage cross section between said spaced guiding vanes being considerably less than the cross'section of said stock inlet of the deviating chamber, that portion of the deviating chamber which is remotest from said stock inlet and is located opposite to said distributing screen means being provided with discharge openings of a small diameter.

14. In a transverse flow distributor having only one deviation of the flow, especially for connection with a headbox of a paper machine, said headbox being provided with a slice and feeding conduit means leading to the latter: a deviating chamber provided with only one paper stock inlet and with only one paper stock outlet, said paper stock inlet being arranged unilaterally of said deviating chamber, said deviating chamber having a substantially constant cross section seen in the direction of said paper stock inlet, a device for steadying the flow of the paper stock and obtaining uniform velocity distribution, said device being designed as distributing screen means arranged in said stock outlet and including guiding vanes each having a length equalling at least a multiple of the thickness thereof and said vanes extending substantially perpendicular to the direction of the inflow of the stock and being slightly spaced from each other, the remaining free passage cross section between said spaced guiding vanes being considerably less than the cross section of said stock inlet of the deviating chamber, and discharge conduit mcans connected to said feeding conduit means near at least one side wall thereof for withdrawing stock from the marginal zones of the stock flow adjacent said'wall.

References Cited in the file of this patent UNITED STATES PATENTS 809,073 McNaught J an. 2, 1906 2,281,293 Lang Apr. 28, 1942 2,566,450 Hornbostel Sept. 4, 1951 2,688,905 Hornbostel Sept. 14, 1951 2,736,247 Hornbostel Feb. 28, 1956 2,737,087 Bennett Mar. 6, 1956 

